Alimentary System
Stomach, Forestomach - Ectopic Tissue
Narrative
Comment:
Ectopic tissue can be present in the lamina propria (primarily), submucosa, or subserosa of
the forestomach. Ectopic tissue can be of any type, but pancreas (Figure 1
and Figure 2), liver (Figure 3 and Figure 4), and intestine (Figure 5) are common. In some cases, it can be associated with
hyperplasia of the overlying squamous epithelium. With ectopic intestine, the presence of gutassociated
lymphoid tissue should not be mistaken for inflammation. Ectopic tissue is considered an
incidental finding.
the forestomach. Ectopic tissue can be of any type, but pancreas (Figure 1
and Figure 2), liver (Figure 3 and Figure 4), and intestine (Figure 5) are common. In some cases, it can be associated withhyperplasia of the overlying squamous epithelium. With ectopic intestine, the presence of gutassociated
lymphoid tissue should not be mistaken for inflammation. Ectopic tissue is considered an
incidental finding.
Recommendations:
Whenever present, ectopic tissue should be diagnosed but not graded. The diagnosis should be modified with the tissue of origin.
References:
Bertram TA, Markovits JE, Juliana MM. 1996. Non-proliferative lesions of the alimentary canal in rats GI-1. In Guides for Toxicologic Pathology. STP/ARP/AFIP, Washington, DC, 1-16.
Full Text: https://www.toxpath.org/docs/SSNDC/GINonproliferativeRat.pdfFrantz JD, Betton GR, Cartwright ME, Crissman JW, Macklin AW, Maronpot RR. 1991. Proliferative lesions of the non-glandular and glandular stomach in rats. GI-3. In Guides for Toxicologic Pathology. STP/ARP/AFIP, Washington, DC, 1-20.
Full Text: https://www.toxpath.org/docs/SSNDC/StomachProliferativeRat.pdf
Stomach, Forestomach - Ectopic pancreas in a female B6C3F1 mouse from a chronic study. Ectopic pancreatic acinar cells are present in the submucosa of the forestomach (arrow).
All Images
Stomach, Forestomach - Ectopic pancreas in a female B6C3F1 mouse from a chronic study. Ectopic pancreatic acinar cells are present in the submucosa of the forestomach (arrow).
Stomach, Forestomach - Ectopic pancreas in a female B6C3F1 mouse from a chronic study (higher magnification of Figure 1). Ectopic pancreatic acinar cells are present in the submucosa of the forestomach.
Stomach, Forestomach - Ectopic liver in a female F344/N rat from a chronic study. Ectopic hepatocytes (arrows) are present in the submucosa adjacent to the limiting ridge.
Stomach, Forestomach - Ectopic liver in a female F344/N rat from a chronic study (higher magnification of Figure 3). Ectopic hepatocytes are present in the submucosa adjacent to the limiting ridge.
Stomach, Forestomach - Ectopic intestine in a male F344/N rat from a chronic study. The submucosa is expanded by a focus of ectopic intestine with gut associated lymphoid tissue (arrow).